[Add] solved solutions

cpp/FLOW018.cpp

@@ -0,0 +1,26 @@
+#include <iostream>
+
+using namespace std;
+
+unsigned long long int fact(int n)
+{
+    unsigned long long int x = 1;
+    int i;
+    for (i = 1; i <= n; i++)
+    {
+        x *= i;
+    }
+    return x;
+}
+
+int main()
+{
+    int t, n;
+    cin >> t;
+    while (t--)
+    {
+        cin >> n;
+        cout << fact(n) << endl;
+    }
+    return 0;
+}